转换垫BLOB，然后返回到垫 [英] Convert Mat to Blob and then back to Mat

问题描述

基本上我特林使用识别OpenCV的Andr​​oid的应对
我需要转换一个通过inputFrame.gray（）人脸检测期间收到垫形象;在CvCameraViewFrame成斑点是一个byte []保存到SQLite数据库，然后同时识别转换这个字节[]回可以在.cpp文件中使用JNI中的文件夹中识别code垫子文件是原生。

解决方案

这竟然是很容易与机器人板载方法：

 进口org.opencv.core.Mat;进口android.content.Context;
进口android.content.ContentValues​​;
进口android.database.Cursor;
进口android.database.sqlite.SQLiteDatabase;
进口android.database.sqlite.SQLiteDatabase.CursorFactory;
进口android.database.sqlite.SQLiteOpenHelper;类SqTable扩展SQLiteOpenHelper {
    字符串表=MYDB;    公共SQLTABLE（上下文的背景下，字符串名称，CursorFactory工厂，诠释的版本）{
        超（背景下，名称，厂家，版本）;
    }    @覆盖
    公共无效的onCreate（SQLiteDatabase DB）{
        db.execSQL（CREATE TABLE+表+（Name文本UNIQUE，T INTEGER，W INTEGER，H INTEGER，PIX BLOB）;）;
    }    @覆盖
    公共无效onUpgrade（SQLiteDatabase为arg0，ARG1 INT，INT ARG2）{
    }    公共无效dbput（字符串名称，板M）{
        长为nbytes = m.total（）* m.elemSize（）;
        字节[]字节=新字节[（INT）为nbytes]
        m.get（0，0，字节）;        dbput（姓名，m.type（），m.cols（），m.rows（），字节）;
    }    公共无效dbput（字符串名称，诠释T，INT W，INT小时，字节[]字节）{
        Log.d（dbput，名称+，+ T +，+ W +的x+ H）;
        SQLiteDatabase分贝= this.getWritableDatabase（）;
        ContentValues​​值=新ContentValues​​（）;
        values​​.put（名，名）;
        values​​.put（T，T）;
        values​​.put（W，w）的;
        values​​.put（H中，h）;
        values​​.put（PIX，字节）;
        db.insert（表，空，价值）;
        db.close（）;
    }     公共垫dbget（字符串名称）{
        SQLiteDatabase分贝= this.getReadableDatabase（）;
        的String [] =列{T型，W，H，PIX};
        光标光标= db.query（表，列，名=？，
                新的String []（名称），//ð。选择ARGS
                空，//即通过...分组
                空，// F。有
                空，//克为了通过
                空值）; // H。限制        如果（指针！= NULL）
            cursor.moveToFirst（）;        INT T = cursor.getInt（0）;
        INT W = cursor.getInt（1）;
        INT H = cursor.getInt（2）;
        字节[] P = cursor.getBlob（3）;
        板M =新垫（H，W，T）;
        m.put（0,0，p）的;
        Log.d（dbget（+名称+），m.toString（））;
        返回米;
    }
};//在你以后的活动中使用：
SQLTABLE SQL =新SQLTABLE（这一点，IMGS，NULL，1）;
板M =新的垫（200,400，CvType.CV_8UC3，新的标量（0,100,0））;
Core.putText（男，世界（〜），新的点（30,80），Core.FONT_HERSHEY_SCRIPT_SIMPLEX，2.2，新的标量（200200200））;
sql.dbput（你好，M）;
//板M = sql.dbget（你好）;
 

Basically I am tring to Face Recognition using OpenCV Android I need to convert Mat image that is received during face detection via inputFrame.gray(); in CvCameraViewFrame into a Blob that is a byte[] to save into SQLite Database and then while recognition convert this byte[] back to a Mat file that can be used in .cpp files in jni folder as recognition code is native.

解决方案

[edit]

it turned out to be quite easy with androids onboard methods:

import org.opencv.core.Mat;

import android.content.Context;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

class SqTable extends SQLiteOpenHelper {
    String table = "mydb";

    public SqlTable(Context context, String name, CursorFactory factory, int version) {
        super(context, name, factory, version);     
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table "+table+" (name TEXT UNIQUE, t INTEGER, w INTEGER, h INTEGER, pix BLOB);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    }

    public void dbput(String name, Mat m) {
        long nbytes = m.total() * m.elemSize();
        byte[] bytes = new byte[ (int)nbytes ];
        m.get(0, 0,bytes);

        dbput(name, m.type(), m.cols(), m.rows(), bytes); 
    }

    public void dbput(String name, int t, int w, int h, byte[] bytes) {
        Log.d("dbput", name + " " + t + " " + w + "x" + h);
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("name", name);
        values.put("t", t); 
        values.put("w", w); 
        values.put("h", h); 
        values.put("pix", bytes);
        db.insert(table, null, values);
        db.close();
    }

     public Mat dbget(String name) {
        SQLiteDatabase db = this.getReadableDatabase();
        String [] columns = {"t","w","h","pix"};
        Cursor cursor = db.query(table,columns," name = ?", 
                new String[] { name }, // d. selections args
                null, // e. group by
                null, // f. having
                null, // g. order by
                null); // h. limit

        if (cursor != null)
            cursor.moveToFirst();

        int t = cursor.getInt(0);
        int w = cursor.getInt(1);
        int h = cursor.getInt(2);
        byte[] p = cursor.getBlob(3);
        Mat m = new Mat(h,w,t);
        m.put(0,0,p);
        Log.d("dbget("+name+")", m.toString());
        return m;
    }
};

// later use in your Activity:
SqlTable sql = new SqlTable(this,"imgs",null,1);
Mat m = new Mat(200,400, CvType.CV_8UC3,new Scalar(0,100,0));
Core.putText(m, "world (~)", new Point(30,80), Core.FONT_HERSHEY_SCRIPT_SIMPLEX, 2.2, new          Scalar(200,200,200));
sql.dbput("hello",m);
// Mat m = sql.dbget("hello");

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